Blank stripping apparatus for rotary cutters



July 7, 1970 KUEHN 3,518,922

BLANK STRIPPING APPARATUS FOR ROTARY CUTTERS Filed 001;. 23. 1967 2 Sheets-Sheet 1 INVENTOR. FEEDER/6K P KUEHN .Fuly 7, 1970 F. R. KUEHN BLANK STRIPPING APPARATUS FOR ROTARY CUTTERS Filed 001;. 23. 1967 2 Sheets-Sheet 2 INVENTOR. FREDERICK R. Kl/EHN g, 3AM

United States Patent 3,518,922 BLANK STRIPPING APPARATUS FOR ROTARY CUTTERS Frederick R. Kuehn, Baltimore, Md., assignor to Koppers Company, Inc., a corporation of Delaware Filed Oct. 23, 1967, Ser. No. 682,707 Int. Cl. B31!) 1/14 US. Cl. 93-582 3 Claims ABSTRACT OF THE DISCLOSURE Apparatus for stripping corrugated paperboard blanks from rotary cutters used to slot blanks during their manufacture by storing, as latent energy, the pressure exerted against the blanks during the cutting of the slot and releasing the energy to overcome the tendency of the blanks to adhere to the slotter blade on one of the cutters, comprising a stripper assembly fixed to the slotter blade so that the tendency to smear any printed material on the blanks is eliminated because the stripping apparatus contacts the blank only during cutting of the slot. In a preferred embodiment, the stripper assembly comprises an angle clip having one leg mounted on the side of the slotter blade and its second leg extending axially and perpendicularly to the slotter blade and extending circumferentially substantially the length of and parallel to the slotter blade, and an elastomeric material secured to the second leg and extending radially outward therefrom and adjacent to the slotter blade and into the tangential plane of blanks passing between the rotary cutters during the slotting operation.

BACKGROUND OF THE INVENTION Field of the invention This invention relates generally to cutting and more particularly to a resiliently mounted stripping tool for radial movement of a product out of contact with a rotary cutting tool.

Description of the prior art In the manufacture of corrugated paperboard cartons, fiat paperboard blanks are fed sequentially into a conventional printer-slotter machine which prints, scores and slots the paperboard blanks at prearranged locations to define flaps which are later folded over to form finished cartons.

Slotting is conventionally accomplished by feeding blanks between spaced pairs of coacting upper and lower slotter heads. Each of the upper slotter heads is provided with two or more angularly spaced knife blades attached to the slotter head and extending radially outward from an annular shoulder on the head. Each of the lower slotter heads is provided with a peripheral groove which receives the cutting edge of the upper slotter knife blades. As blanks are fed between the slotter heads, one blade cuts a slot in the leading edge and the other cuts a slot in the trailing edge of the blanks.

The blanks have a tendency to adhere to the sides of the knife blade during the slotting of the leading edge of the blank causing them to wrap around the slotter head, consequently jamming the slotter heads or impeding the flow and slotting of successive blanks.

The conventional means utilized to prevent this occur rence consists of one or more stripper bars or fingers independently mounted above the plane of travel of the blanks and downstream from the upper slotter head to catch and depress the blanks as they exit from the slotter heads.

One such stripping means is demonstrated in FIG. 12 of Swift Pat. No. 1,977,812, which shows a stripper frame terminating in rearwardly presented stripper fingers disposed slightly above the plane of travel of the blanks passing between the slotter heads and constructed so as to permit the passage of the slotter knife blade between the stripper fingers.

The most common disadvantage of independently mounted stripper bars or fingers is that while preventing a slotted blank from adhering to and following the slotter blade, they also have a tendency to smear the ink on freshly printed blanks. Another disadvantage of most stripper bars is that they are mounted so as to pass the stripper bar or fingers through grooves in the upper slotter head. Provision must therefore be made for repositioning the complete stripper assembly as well as the slotter heads when the slot spacing changes for different width blanks.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide blank stripping apparatus for rotary cutters constructed in a manner to prevent smearing of ink on the blanks and which are laterally spaced concurrently with spacing of the rotary cutters.

These and other objects and novel features are generally accomplished by providing a stripping device mounted on the side of the slotter knife blade for rota tion therewith. In this manner, the strippers are laterally spaced along with the cutting heads so that no further adjustment is necessary. Since the strippers rotate with the blades, their peripheral speed equals the lineal speed of the blanks being slotted by the blades and accordingly, the strippers do not drag across the ink on the blank as would be the case with fixed bar or finger strippers.

The stripping apparatus in the preferred embodiment comprises a band of an elastomeric or resilient material secured to a support bracket mounted on the side of a slotter knife blade. The stripping apparatus and knife blade are then mounted to the upper slotter head of a printer slotter. In operation, the elastomeric band is compressed by the blank passing between the slotting heads and consequently this compressive force urges the blank away from the slotter heads so that it does not adhere to and tend to wrap around the rotary head.

Another advantageous feature is that the support bracket is constructed for rapid assembly to and disassembly from the slotter knife blade thereby enabling the machine operator to rapidly replace worn knife blades or install blades of different lengths.

A further advantageous feature is that the stripping apparatus is inherently more economical to manufacture, install and operate than conventional blank stripping means.

The above and further objects and novel features of the invention will appear more fully from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are not intended as a definition of the invention but are for the purpose of illustration only.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings wherein like parts are marked alike,

FIG. 1 is an isometric view illustrating the preferred construction of the novel stripping apparatus mounted to a rotary cutter shown slotting a carton blank;

FIG. 2 is a fragmentary axial view in partial cross section of the stripping apparatus shown in FIG. 1 acting against a carton blank being slotted;

FIG. 3 is a radial view in partial cross-section taken along line III-III of FIG. 2; and

FIG. 4 is an isometric view illustrating an alternate embodiment of the novel stripping apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the invention is illustrated herein as being incorporated in a pair of coacting rotary cutters of the type having a segmental knife blade 28 secured to one of said cutters 12. A resilient stripping means 44 is secured adjacent one side of the blade and extends substantially the length of the blade. The stripping means has a blank engaging surface 11 adjacent the cutting edge of said blade. This stripping means is adapted to be compressed by a blank 36 passing between the coacting rotary cutters 10 for thereafter urging the blank away from the blade, thereby overcoming any tendency of the blank to adhere to the blade.

Referring now to the drawings, a conventional rotary slotting apparatus denoted generally as 10, FIGS. 1, 2 and 3, comprises a pair of coacting upper and lower slotter heads 12 and 14 slidably mounted on a pair of parallel shafts 16 and 18. Slotter head 12 has an axial T-slot 20 in which T-bolts 22 are slidably secured. The bolt shanks 24 of T-bolts 22 extend axially outward from an axial T-slot 20. Slotter knife blades 28 and 29 rest on an annular shoulder 30 of slotter head 12 and are secured thereto by nuts 32 threaded on T-bolts 22 which extend through the slotter blades 28 and 29.

The lower slotter head 14 is provided with a circumferential cutting groove 34 located in its periphery which forms a cooperative receiving cutter for slotter blades 28 and 29. The upper and lower slotter heads 12 and 14 are aligned so that when the upper head 12 rotates, the slotter blades 28 and 29 are brought into contact with a creased or scored paperboard blank 36 and are received by the circumferential groove 34 on rotating slotter head 14 so that the cutting edges 33 of slotter blades 28' and 29 cut slots 35 in the leading edge 38 and trailing edge 40 of blank 36 to form flaps 39a and 39b. Slotter blades 28 and 29, which have a greater radius than slotter head 12, are positioned on the upper slotter head 12 at preselected angular intervals to cut slots 35 at the correct locations at the leading and trailing edges, 38 and 40 respectively, of the blank 36. The desired length of the slots 35 determine the length of slotter blades 28 and 29 required. The length of the blades can be increased by placing slotter blades together around the slotter head 12. When blanks 36 of different lengths are to be slotted, the annular location of slotter blades 28 and 29 can quickly be changed by loosening nut 32 on T-bolt 22 and sliding the blades to a new position in order to correctly cut slots 35 at the desired locations.

Although only one blade 28 is required to cut the slot illustrated in FIG. 1, two such blades are shown adjacent each other to show how each blade may be provided with a stripping assembly 44. Conventionally, blade 28 is provided with a radially extended tip portion 42 for slotting the leading edge 38 of blank 36.

According to this invention, slotter blade 28 which is to cut a slot 35 in the leading edge 38 of blank 36 is provided with a stripping assembly, denoted generally as 44, FIGS. 1, 2 and 3. This stripping assembly comprises a rigid support bracket 46 and a resilient or elastomeric stripping band 48 secured thereto. Support bracket 46, FIG. 3, is L-shaped in cross-section and has a length extending, FIG. 2, substantially the arc length of blade 28. Leg portion 50 of bracket 46 extends axially outward and perpendicular to slotter blade 28 and has radial inner and outer surfaces 51A and 51B corresponding to the same radius of curvature of slotter blade 28 and serves as a base support for resilient or elastomeric band 48. Leg portion 52 extends parallel to slotter blade 28 and it and slotter blade 28 are secured to slotter head 12 by T-bolt 28 and nut 32 extending through a radial slot 26 in blade 28 and a radial slot 54 in bracket 46.

The elastomeric stripping band 48 extends the length of and is bonded to the outer radial surface 51B of leg portion 50 and has convoluted ends 56 disposed radially inward to secure stripping band 48 to leg 50.

The ends of band 48 may terminate substantially evenly with the ends of leg portion 50 if desired, but convoluted ends 56 are preferred since the band 48 is compressed by engagement with blanks 36. The rounded ends provide for more gradual engagement and compression so that there is less tendency for smearing to occur if there is printing on the flap.

Elastomeric band 48 is substantially rectangular in cross-section and, as best illustrated in FIG. 3 of the drawings, its width is substantially the same as the axially extended leg portion 50, except that there is a slight clearance, for example inch, between the inner face 47 of band 48 and the outer face 49, FIG. 3, of slotter blade 28 to prevent the two surfaces from binding against each other when band 48 is being compressed or decompressed. The height of band 48 extends from the radial outer surface 51B of leg portion 50 to substantially near the outer radial edge of slotter blade 28, as shown. The height of band 48 is preferably less than the height of blade 28 so that there is no tendency for the band to be deformed into the cutting path of the blade.

Elastomeric band 48 is preferably rubber, either natural or synthetic, although it can be made of polyurethane or some other form of plastic. The hardness of the rubber is chosen so that it has sufficient stiffness to urge the blanks away from the slotter blades and yet be soft enough to be compressed by the blanks without crushing them. A durometer of 20-40 hardness has been found to be satisfactory when used against corrugated paperboard blanks. The radial thickness of band 48 will depend somewhat upon the hardness of the rubber used. The band should be thick enough to accommodate deformation by the blank Without becoming so stiff that it crushes the blank. The axial width of the band is not critical. However, the wider it is made, the less chance there is that it will indent the blank. For example, a thickness and Width of about twice the thickness of a conventional slotter blade 28 has been found to be satisfactory.

The band 48 may be secured to leg 50' by bonding in the known manner or by, for example, an adhesive or by countersunk rivets.

OPERATION In operation, as the slotter blade 28 passes through the flap 39a of blank 36, the elastomeric band 48 comes into contact with blank 36, as shown by the shaded portions in FIG. 1, and is compressed thereby. As the blade 28 continues its cut, the band is subject to the compression and acts as a reservoir to store this compressive force as latent energy. As the blade emerges from the cut, its leading edge begins to rise from the slot. At this point, the stored compression force begins to be released at the front end of band 48 and the latent energy is released by band 48 and acts to urge the blank 36 away from the rising slotter blade 28 immediately behind the tangent point of contact between the blank and the lower slotter head 14. Since the band 48 extends sub stantially the length of blade 28, it remains in contact with blank 36 substantially throughout the length of the slot 35 and continuously urges the blank away from blade 28.

An advantage of this invention is that band 48 contacts blank 36 only during the cutting of the slot in flap 39a and is in rolling contact with blank 36 to this limited extent. Thus, there is little, if any, tendency to smear any fresh printing on the portions of the blank between the flaps 39a and 39b.

A further advantage of the invention is that, to space the stripping assemblies 44 laterally across the rotary slotting apparatus to accommodate differently spaced slots, it is merely necessary to space the slotter heads 12 and 14 in the conventional manner. The stripping assemblies 44, being secured to slotter heads 12, are thereby automatically located.

It is common in the box making operation to use the same machine to make blanks having different size flaps and thus different length slots. conventionally, the slotter head 12 is adapted to receive slotter blades 28 and 29 of different lengths so that different length slots can be cut. Preferably, stripping assemblies 44 are provided which have a length corresponding to the length of the cutting blade being used. If only a slightly larger blade is used, the stripping assembly 44 for a shorter blade may be used. Since the support bracket 46 is provided with a U-shaped radial slot '54 for mounting the bracket 46 to blade 28, the stripping assembly 44 is easily removed and mounted along with its associated slotter blade.

OTHER CONSTRUCTIONS FIG. 4 illustrates another construction of the stripping assembly 44 of FIGS. 1, 2 and 3. In this assembly, generally designated as 58, the elastomeric portion comprises an endless band 60 encircling the axially extending leg 64 of bracket 62. Band '60 is retained on leg 64 by annularly extending lugs 66 provided on the ends of leg 64.

The construction of 'FIG. 4 has the added advantage in that worn bands 60 can be easily replaced by stretching a new band over the lugs 66. No adhesives or other fastening is required. In addition, the band 60 may be rotated around leg 64 to present an unused portion for contact with the blanks 36.

The foregoing constructions provide an economical blank stripping device for rotary cutter machines and particularly printer-slotter machines which are easily mounted and placed in operation. Their use is particularly advantageous where problems of ink-smearing are encountered.

Having thus described the invention in its best embodiment and mode of operation, what is desired to be claimed by Letters Patent is:

1. Apparatus for stripping blanks from one of a pair of coacting rotary slotter heads in a printer-slotter machine comprising:

a segmental knife blade secured to said one of said heads for cooperative cutting engagement with the other of said heads;

a support bracket secured to said blade and having a first leg portion extending axially outward from and substantially perpendicular to said blade, said first leg portion having an outer arcuate periphery, and a second leg portion connected to said first leg portion and extending radially inward from and substantially perpendicular to said first leg portion and adjacent one side of said blade, said second leg portion having a radial slot centrally located therein extending to the inner radial periphery thereof;

a fastener secured to said head and extending through said blade and said radial slot for securing said blade and said bracket to said head; and

a band of elastomeric material secured to and extending radially outward from. said outer periphery of said first leg portion, said arcuate band extend ing substantially the circumferential length of and adjacent to one side of said blade and having an arcuate blank-engaging surface substantially adjacent the cutting edge of said blade, said band having convoluted ends surrounding the outer ends of said first leg portion, said band adapted to be compressed against said support bracket by a blank passing between said coacting rotary slotting heads for urging said blank away from said blade thereby overcoming any tendency of said blank to adhere to said blade.

2. The apparatus of claim 1 wherein said band of elastomeric material comprises an endless band encircling said first leg portion of said bracket.

3. The apparatus of claim 2 wherein said first leg portion includes an annularly extending lug portion on each end thereof for securing said endless band on said bracket.

References Cited UNITED STATES PATENTS 1,977,812 10/1934 Swift 93--58.2 3,198,093 8/1965 Kirby et al. 93-58.2 3,277,756 10/1966 Jardins et a1. 83-116 BERNARD STICKNEY, Primary Examiner US. Cl. X.R. 

